Field of the Invention
This invention relates to a method of accurately determining on a continuous basis the amount of the fluid content with a smaller specific gravity in airtightly sealed flexible containers containing contents with different specific gravities that are automatically separated from each other when held to a stationary state such as liquid and gas or water and oil.
In the food industry, a cooked liquid food such as soup or stew contained in an airtightly sealed flexible container, or a retort pouch, with air or inert gas is subjected to an operation of so-called rotary retorting treatment for preservability, where the food is heated under high pressure while rotating the retort pouch.
The inventor of the present invention has found that the amount of gas content of each retort pouch significantly affects the sterilizing efficiency of the rotary retorting operation in terms of rate and extent of sterilization. The sterilizing effect of the rotary retorting treatment is particularly remarkable when the retort pouch contains gas by 2 to 50%. Additionally, the sterilizing effect on treated retort pouches is held to a highly uniform level and the degradation of the food content of the retort pouch by-overheating is minimized when the deviation in the gas content is confined between-3 and 10% among treated retort pouches.
On the other hand, if a retort pouch contains both liquid and gas and the viscosity of the liquid content is low, the liquid content is heavily affected by inertia to such an extent that the operation of determining the amount of the liquid content cannot be carried out immediately after the moved in container is held to a stationary state. The inventor of the present invention has found after a series of experiments that this problem is particularly remarkable when the coefficient of viscosity of the liquid content is lower than 5,000 CP.
Since a retort pouch made of flexible film is pliable and hence has a variable profile, it is very difficult to measure and regulate the amount of gas content or, more strictly speaking, the ratio of the gas content to the liquid content contained in it when compared with a rigid or quasi-rigid container such as a cup or a tray. No instruments are known to date that can quickly and accurately measure the gas content of retort pouches.
Additionally, as described above, if a retort pouch contains both liquid and gas and the viscosity of the liquid content is low, liquid content is heavily affected by inertia to such an extent that the operation of determining the amount of the liquid content cannot be carried out immediately after the moved in container is held to a stationary state. It has been discovered by the inventor of the present invention that this problem is particularly remarkable when the coefficient of viscosity of the liquid content is lower than 5,000 CP. Because of these and other problems, it has been believed to be difficult to measure on a continuous basis in a commercially feasible way the amount of the fluid content with a smaller specific gravity in airtightly sealed flexible containers containing contents with different specific gravities that are automatically separated from each other when held to a stationary state such as liquid and gas or water and oil.
Meanwhile, a measurement of the surface temperature distribution of an airtightly sealed container of the type under consideration shows that, if letters and/or decorative design segments are printed on the surface, the radiation of electromagnetic waves from the surface is differentiated between printed areas and plain areas so that no accurate measurement of surface temperature distribution can be achieved on such a container.
In view of the above identified technological problems, it is therefore an object of the present invention to provide a method of accurately measuring the amount of the fluid content with a smaller specific gravity in airtightly sealed flexible containers containing contents with different specific gravities that are automatically separated from each other when held to a stationary state such as liquid and gas or water and oil.
It is another object of the present invention to provide a method of accurately measuring on a continuous basis the amount of the fluid content with a smaller specific gravity in airtightly sealed flexible containers containing contents with different specific gravities that are automatically separated from each other when held to a stationary state such as liquid and gas or water and oil.
It is still another object of the present invention to provide a pressure plate to be used for accurately measuring on a continuous basis the amount of the fluid content with a smaller specific gravity in airtightly sealed flexible containers containing contents with different specific gravities that are automatically separated from each other when held to a stationary state such as liquid and gas or water and oil.
It is a further object of the present invention to provide a method of accurately measuring the surface temperature distribution of an object of examination including but not limited to an airtightly sealed container that carries printed letters and/or decorative design segments on the surface and irradiate electromagnetic waves therefrom.